Global environmental changes are causing Lyme disease to emerge in Europe. The life cycle of Ixodes ricinus, the tick vector of Lyme disease, involves an ontogenetic niche shift, from the larval and nymphal stages utilizing a wide range of hosts, picking up the pathogens causing Lyme disease from small vertebrates, to the adult stage depending on larger (non-transmission) hosts, typically deer. Because of this complexity the role of different host species for emergence of Lyme disease remains controversial. Here, by analysing long-term data on incidence in humans over a broad geographical scale in Norway, we show that both high spatial and temporal deer population density increase Lyme disease incidence. However, the trajectories of deer population sizes play an overall limited role for the recent emergence of the disease. Our study suggests that managing deer populations will have some effect on disease incidence, but that Lyme disease may nevertheless increase as multiple drivers are involved.

High throughput sequencing has become a powerful tool for fungal ecologists to explore the diversity and composition of fungal communities. However, various biases and errors are associated with the new sequencing techniques that must be handled properly. We here provide evidence for a source of error that has not yet been taken into account. During amplicon pyrosequencing we incorporate tags in both ends of the amplicons, which allows us to check for tag coherence after sequencing. In several studies we have observed that a small proportion of the resulting sequences possess novel tag combinations. Our observations cannot be explained by primer contamination or PCR chimaeras. This indicates that some DNA fragments switch tags during laboratory setup. If not controlled for, this will cause numerous false positives in downstream analyses. In most amplicon pyrosequencing studies of fungal communities, amplicons are typically tagged in one end only. We suggest that amplicons should be tagged in both ends before pyrosequencing to control for tag switching.

Virtually all land plants host fungal endophytes. However, the composition and diversity of fungal endophytes growing in a range of wild grasses serving as food sources for grazing animals remains largely unexplored. Avenella flexuosa, a perennial grass of the family Poaceae, is abundant in the cold temperate regions of Europe. In alpine habitats of Norway, this grass accounts for ~30% of the diet for about 2.1 million domestic sheep (Ovis aries) that are released for summer grazing yearly. The aim of the present study was to investigate the effect of grazing on the species diversity and composition of endophytes appearing in A. flexuosa in an alpine habitat in Norway. Plants were sampled from plots exposed to grazing (80 sheep per km2) as well as control plots (no grazing). The study area is part of a long-term study measuring the effects of grazing on alpine ecosystems, and has been closely monitored and exposed to controlled grazing pressure for seven years prior to sampling. The presence of fungal endophytes was assessed with traditional culturing methods followed by ITS sequence identification. In parallel, grass bulk samples were screened for total fungal diversity using 454 pyrosequencing. The results of the study will be presented